Site Map

Value Added Catalogs

In addition to the primary SDSS-III photometry and spectroscopy, there are a few extra catalogs created by our collaborators that are distributed through the SAS.

SEGUE Value-Added Catalogs

[α/Fe] Values

This catalog provides the [α/Fe] ratios for SDSS and SEGUE stars from Lee et al. 2011. They are able to determine [α/Fe] abundance to an error less than 0.1 dex for stars with Teff between 4500 and 7500 K, log g between 1.5 and 5.0, [Fe/H] between -1.4 and +0.3, and S/N greater than 20. To accomplish this precision for a star with [Fe/H] < -1.4, a spectrum with S/N larger than 25 is required. The [α/Fe] abundance ranges from -0.1 to +0.6.

These abundance measurements were tested on degraded ELODIE spectra, samples of high- (R=15,000) and medium-resolution (R=6,000) spectra, and six open and globular clusters.

Accounting for Observational Biases in SEGUE

Certain aspects of the SEGUE target selection algorithm, in addition to components of the survey's design, will create observational biases in the sample. For example, SEGUE assigns the same number of spectroscopic fibers to each plate, regardless of the stellar density of the line-of-sight. As the stellar number density changes over the SEGUE footprint, investigations using the survey data must correct for this variable sampling to represent the true underlying Milky Way stellar distributions. In addition, some target types will require corrections for the color, magnitude, and/or proper motion selection.

Schlesinger et al. 2012 investigated these biases for cool dwarf stars in the SEGUE sample. This value-added catalog explains a technique to constrain and account for the observational biases in SEGUE. It also provides a series of weights that can be used to determine a complete, unbiased SEGUE G- and K-dwarf sample.

Duplicate Observations

A list of identifiers for repeat spectroscopic observations of individual photometric targets in SEGUE. These are particularly useful for testing consistency of the SSPP.

Large Scale Structure Galaxy Catalogs

The galaxy catalogs used in the DR9 large scale structure analyses, e.g., Anderson et al. (2012) and Parejko et al. (2012) (which will be linked when it is available) are available from the SAS. The files in the catalogs are described in the data model on


Bovy et al. (2011) describes a technique for QSO target selection based on an extreme deconvolution method, which models the distribution of quasars and stars in color-color space, including their errors. The associated catalog is available here. The files in the catalog are described in the data model.

Photometric Redshift Distributions

Sheldon et al. (2012) have created a set of photometric redshift probability distributions for galaxies in the SDSS-III imaging data. The catalog is available here. The files in the catalog are described in the data model.

Galaxy Parameters

Catalogs of galaxy properties such as stellar masses, ages, stellar formation rates, and velocity dispersions are described on the Galaxy Products page.

QSO Catalog

The French Participation Group (FPG) to SDSS-III has produced a quasar catalog, described in detail in Pâris et al. (2012) (accepted by A&A) and summarized on the DR9Q algorithms page. Quick links to the files:

DR9Q FITS ASCII Primary catalog
DR9Q_sup FITS ASCII Supplemental quasars added after the "freeze" of the catalog
DR9Q_unconfirmed FITS ASCII Unconfirmed, possible QSO? quasars

BOSS Lyman-alpha forest Sample

The BOSS Lyman-alpha forest sample provides a curated set of QSO spectra useful for Lyman-alpha forest studies, including QSO continuum fits, additional data quality masks, corrections for damped Lyman-alpha systems (DLAs), and corrections to the default noise model.